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LDP Hazitall just arrived

P

PacMan

Experienced Member
Joined
Nov 13, 2008
Messages
73
Location
Sweden
I just received an LDP Hazitall multi I/O board that I won on eBay two weeks ago. It looks as if it is in excellent condition, just a little dust on it.

hazitall.JPG


I don't have any manuals for it and google doesn't turn up anything useful except for Herbs web pages. So I am going to write a small program that scans the I/O addresses and hook a logic analyzer to see where the chip select signals triggers.

One interesting thing is that it has a RTC on board, the red connector on the top obviously plugs into a battery module.

I'm going to have a few great hours of fun now :mrgreen:

/P
 
Arghhh, got bitten by the S-100 compatibility "bug" and spent way to much time on analyzing the wrong things :mad: Turns out that the Hazitall boards has a ground pad in connector pin 53 instead of SSW_DSBL* that my CPU board has. Which of course disables the CPU board from start.

After finding that, I managed to work out the following IO map:

Code: 
0xC0 - 0xC3  UART1
0xC4 - 0xC7  UART2
0xC8 - 0xCB  PPI
0xCC - 0xCF  8253
0xE0 - 0xFF  RTC
Now I only need to work out what timer channels goes to what UART and we're in business :-D

/P
 
Some progress....

UART1 has its TxC and RxC connected to the Timer 0 output pin of the PIT and UART2 has its clock pins connected to Timer 1. The oscillator controlling the PIT was controlled by a 4.0MHz Crystal which a weird frequency for generating proper UART baud rates. I replaced it with a 3.6864 Mhz crystal and programmed the PIT to divide by 12 so now I have a clean and nice 153600 KHz clock signal in to my UART. Verified it with my scope as well.

My first simple tests to send data out on the UART indicates that there still is some problem with the board. The UART (when i measure directly on the UART) reports that the TxRDY bit is set and the UART is ready to transmit. But the processor fails to recognize the TxRDY condition for some reason. Either it is my Z80 programming skills that is defeating me or there is something weird with the board.

RTS* is connected to CTS* on the RS232 side and I have programmed the RTS* output to pull low and have verified that it is working as expected.

How does this look to you guys ?

Code: 
UART0_DATA    equ     0C0h
UART0_CTL     equ     0C1h
UART0_STAT    equ     0C1h
UART0_TXRDY   equ      001h
;
; Send one character
putchar:
    push  AF
pc1:
    in    A, UART0_STAT
    bit   UART0_TXRDY, A
    jr    NZ, pc1
    pop   AF
    out   UART0_DATA, A
    ret

It works in the simulator but I may be missing something here

/P
 
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Are you sure you're checking the right bit and for the right value? I remember programming 16550s on a Z80 system and bit 5 went low to indicate TX readiness. Or are these just a different type of UART?
 
I'm sorry,
I should have mentioned that the UARTs on the board are Intel P8251's. Very antique stuff but they shold hopefully work. The date codes on my devices are 82 but I have an old Intel catalogue from 1976 with it listed so they are indeed antiques.

But to answer your question, yes I am pretty sure that i am checking the correct status bit.

However..... sitting here reading my post over again I suddenly realize what I did wrong.....

It should be the bit number not a bit pattern in the Z80 BIT instruction. :oops: Need to change that when I get home.

So it was my poor Z80 skills after all :sneaky:

/P
 
Heh - yes, I noticed you had defined UART0_TXRDY in hex; the BIT instruction is what I was hinting at ;-) I've tripped over that one myself before...
 
8251 bit 0 is TxRDY

Am I nuts or do you have the backplane mounted in a Atari 2600 case?
 
Last edited:
Thanks guys, the problem was with my code.
Now it all works as it should.

Next step will be to get the NoIce debugger up and running on my monstera.

/P
 
Good to hear all's working. That's shaping up to be a great little system you've got there! Might even have to look into get some S100 kit myself to play with... looks like it'd be right up my alley.
 
Just wanted to let you know.... got everything up and running now... finally.
I can compile code with SDCC and then download and debug it in C-code, assembler or both directly using NoIce Debugger. It's a sweeeet setup :)

/Pontus
 
Cool. I've used SDCC before for Z80 stuff and the later versions seem pretty solid. NoIce is new to me though - looks very useful.

I'm thinking about re-doing my homebrew Z80 system using the S100 bus, maybe even throw a CP/M BIOS together for it. It's grown a bit large to be running ribbon cables all over the place and I really can't be bothered to code up my own OS any more!
 
cosam said:
[snip]
I'm thinking about re-doing my homebrew Z80 system using the S100 bus, maybe even throw a CP/M BIOS together for it.
[snip]
Click to expand...

Hi! I have thought about doing an S-100 project as well. Depending on how the S-100 backplane project goes, eventually I'd like to include other S-100 devices in with the N8VEM project. There are a lot of neat home brew computing projects and S-100 would be great if some of the hurdles can be overcome. S-100 power supplies, backplanes, chassis, etc can be problematic but still solveable.

If I were to make my own home brew S-100 system, I'd probably go with an 8080 based system as the S-100 bus is a logical extension of the 8080 bus lines. Some of the early S-100 8080 CPU boards are amazingly simple devices with low part counts. They don't have some features that SBCs normally have like RAM, ROM, and a UART which makes the CPU board less complex. I am thinking an S-100 system with a simple 8080 CPU board, a simple RAM/ROM board, simple serial UART board, etc. I have several S-100 prototype boards at home which have been just waiting patiently for an opportunity.

The simplicity of the S-100 approach of simple modular units is very appealing to me. I also like the Eurocard of the ECB but I have found it to be rather cramped in terms of PCB space at times. Sometimes the complexity of the boards has driven complexity and part density too high IMO.

Thanks and have a nice day!

Andrew Lynch
 
lynchaj said:
Depending on how the S-100 backplane project goes, eventually I'd like to include other S-100 devices in with the N8VEM project.
Click to expand...
Yes, I've been following your backplane project - if I actually had any S100 stuff I'd be volunteering to help test it!

lynchaj said:
If I were to make my own home brew S-100 system, I'd probably go with an 8080 based system as the S-100 bus is a logical extension of the 8080 bus lines.
Click to expand...
I've been looking at that too. I'm swaying towards the Z80 though as I'm familiar with it and, although there's a bit more work interfacing it to the bus, a single +5V supply and a bit more performance seem like a fair trade-off.

lynchaj said:
The simplicity of the S-100 approach of simple modular units is very appealing to me. I also like the Eurocard of the ECB but I have found it to be rather cramped in terms of PCB space at times. Sometimes the complexity of the boards has driven complexity and part density too high IMO.
Click to expand...
The modular approach is what attracts me too. If it wasn't for the price of connectors and such when I started my own Z80 project, I would've built separate cards for CPU, memory, I/O, etc. I think Eurocard is great if you're making PCBs which allow you to cram a fair amount of components onto the board. For prototyping it's nice to have a bit more space so you don't end up tripping over your own wires!
 
manuals

manuals

I just joined the forum. I have a ldp hazital manual that I could copy if it would be of any interest to you.

I have used this board as part of a dedicated factory test system for over twenty years.

I also have several other ldp manuals that I could share if needed.
 
Ron,

I'd love to have a copy of the manual. Would it be possible for you to scan it ? I believe that Howard Harte of Hart Technologies would also like a scanned copy for his on line S-100 manuals.

Thanks
/Pontus
 
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